New global warming science?

On global warming, public policy is where the science was in 1998. Due to new evidence, science has since moved off in a different direction.

The Intergovernmental Panel on Climate Change (IPCC), the UN science body on this matter, is a political body composed mainly of bureaucrats. So far it has resisted acknowledging the new evidence. But as Lord Keynes famously asked, "When the facts change, I change my mind. What do you do, sir?"

Four things have changed since 1998.

First, the new ice cores shows that in the past six global warmings over the past half a million years, the temperature rises occurred on average 800 years before the accompanying rise in atmospheric carbon. Which says that the carbon rises could not have either started or ended the temperature rises, and that there are more powerful forces on global temperatures than atmospheric carbon levels.

This 800 year lag became known and past dispute by 2003, which is very significant. The old low-resolution ice core data, which showed carbon and temperature moving in lockstep for the last half million years, was the only supporting evidence we ever had that carbon caused temperature.

Watch Al Gore's film An Inconvenient Truth carefully. The only reason he presents for believing that carbon emissions cause global warming is the old ice core data.

But now in 2003 we found that temperature causes carbon (a warming ocean releases its dissolved carbon dioxide into the air), not the other way around as previously assumed. By the way, Gore's movie was made in 2005 so he would have known about the new ice core data - it was naughty of him not to mention it.

Second, there is now no evidence to support the idea that carbon emissions cause significant global warming. None. There is plenty of evidence that global warming has occurred, and theory suggests that carbon emissions should raise temperatures (though by how much is hotly disputed), but there are no observations by anyone that implicate carbon emissions as a significant cause of the recent global warming.

The world has spent $50 billion on global warming since 1990, and we have not found any actual evidence that carbon emissions cause global warming. Evidence consists of observations made by someone at some time that support the idea that carbon emissions cause global warming.

Computer models and theoretical calculations are not evidence, they are just theory. Comparisons of model outputs to observed results are not evidence because they cannot prove that the model is always right, only that it was right in some instances.

Third, the satellites that measure the world's temperature all say that the warming trend ended in 2001, that 1998 was the warmest recent year, and that the temperature has dropped about 0.6C in the last year (to the temperature of 1980).

Land based temperature readings are corrupted by the 'urban heat island' effect-urban areas encroaching on thermometer stations warm the micro-climate around the thermometer, due to vegetation changes, concrete, cars, houses. Satellite data is the only temperature data we can trust, but it only goes back to 1979.

The satellites go around 24/7, measuring the temperature across broad swathes of the world, everywhere except the poles. NASA, who report only land data and a little ocean data, report a modest warming trend since 2001 and recent cooling. The other three global temperature records use a mix of satellite and land measurements, or satellite only, and they all show no warming since 2001 and a recent cooling.

Fourth, we looked for the greenhouse signature and could not find it.

Each possible cause of global warming has a different pattern of where in the atmosphere the warming occurs first. The signature of increased greenhouse warming is a hotspot 10 km up in the atmosphere over the tropics.

The hotspot is central to our understanding - if there is no hotspot then either there is no significant increased greenhouse warming, or we don't understand greenhouse and all our climate models are rubbish anyway.

We have been measuring the atmosphere for decades using radiosondes-weather balloons with thermometers that radio back the temperature as the balloon ascends through the atmosphere. They show no hotspot whatsoever.

So we now know for sure that carbon emissions are not a significant cause of the global warming. If we had found the greenhouse signature then I would be an alarmist again instead of a skeptic.

These four changes have rendered our current debate over carbon emissions obsolete. Because the changes occurred slowly as the science on each item became more settled, there was no sudden news flash to make us sit up and take notice.

But now that we are finally coming to terms with how expensive it will be to cut back our carbon emissions, the causes of global warming have suddenly become a topic of major economic importance.

So far that debate has just consisted of a simple sleight of hand: show evidence of global warming, and while the audience is stunned at the implications, simply assert that it is due to carbon emissions. In the mind of the audience, the evidence that global warming has occurred becomes conflated with the alleged cause, and the audience hasn't noticed that the cause was merely asserted, not proved.

If there really was any evidence that carbon emissions caused global warming, don't you think we would have heard all about it ad naseum by now?

Policy makers must grapple with the possibility that global temperatures don't rise over the next decade. Deliberately wrecking the economy for the reasons that later turn out to be bogus hardly seems like a recipe for electoral success.

The onus is on those who want to change things to provide evidence for why the changes are necessary. So now is the time for the government to present any evidence they have that carbon emissions cause global warming. I think you'll find they have none, nowadays.